4,530 research outputs found
Absence of sign problem in the (saddle point approximation of the) nilpotency expansion of QCD at finite chemical potential
We have developed a method to derive the (approximate) quark contribution to
the fermion free energy of QCD on a lattice, at finite temperature and chemical
potential, with Kogut-Susskind fermions in the flavor basis. We show here the
expression at zero temperature. This result has been obtained at the lowest
order of the nilpotency expansion. At this order the well known "sign problem"
does not arise and the quark contribution to the action can be used as a
statistical weight in the Monte Carlo simulations.Comment: 7 pages, presented at the XXVIII International Symposium on Lattice
Field Theory (Lattice 2010), Villasimius, Sardinia, Italy, June 14-19, 201
Transfer matrix for Kogut-Susskind fermions in the spin basis
In the absence of interaction it is well known that the Kogut-Susskind
regularizations of fermions in the spin and flavor basis are equivalent to each
other. In this paper we clarify the difference between the two formulations in
the presence of interaction with gauge fields. We then derive an explicit
expression of the transfer matrix in the spin basis by a unitary transformation
on that one in the flavor basis which is known. The essential key ingredient is
the explicit construction of the fermion Fock space for variables which live on
blocks. Therefore the transfer matrix generates time translations of two
lattice units.Comment: 16 page
Chiral symmetry breaking and quark confinement in the nilpotency expansion of QCD
We apply to lattice QCD a bosonization method previously developed in which
dynamical bosons are generated by time-dependent Bogoliubov transformations.
The transformed action can be studied by an expansion in the inverse of the
nilpotency index, which is the number of fermionic states in the structure
function of composite bosons. When this number diverges the model is solved by
the saddle point method which has a variational interpretation. We give a
stationary covariant solution for a background matter field whose fluctuations
describe mesons. In the saddle point approximations live fermionic
quasiparticles with quark quantum numbers which are confined, in the sense that
they propagate only in pointlike color singlets. Conditions for chiral symmetry
breaking are determined, to be studied numerically, and a derivation of
mesons-nucleons action is outlined.Comment: 33 page
Quark-composites approach to QCD
We present a perturbative approach to QCD based on quark composites, that is
barions and mesons, as fundamental variables.Comment: 4 pages LaTeX, to appear in the proceedings of ``Path Integrals from
peV to TeV'', Florence-Italy, August 25-29, 199
Секвенційні числення композиційно-номінативних модальних логік функціонально-екваційного рівня
Досліджуються композиційно-номінативні модальні та темпоральні логіки функціонально-екваційного рівня. На основі властивостей відношення логічного наслідку для множин формул збудовані числення секвенційного типу для загальних та темпоральних композиційно-номінативних модальних логік такого рівня. Для побудованих числень доведені теореми коректності та повноти
Higher order perturbation theory for the diffusion equation in heterogeneous media: application to layered and slab geometries
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General perturbative approach to the diffusion equation in the presence of absorbing defects: frequency-domain and time-domain results
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